数据绑定到 WPF 树视图中的 SelectedItem [英] Data binding to SelectedItem in a WPF Treeview

问题描述

如何检索在 WPF-treeview 中选择的项目?我想在 XAML 中这样做，因为我想绑定它.

How can I retrieve the item that is selected in a WPF-treeview? I want to do this in XAML, because I want to bind it.

您可能认为它是 SelectedItem，但显然 不存在 是只读的，因此无法使用.

You might think that it is SelectedItem but apparently that does not exist is readonly and therefore unusable.

这就是我想要做的:

<TreeView ItemsSource="{Binding Path=Model.Clusters}" 
            ItemTemplate="{StaticResource ClusterTemplate}"
            SelectedItem="{Binding Path=Model.SelectedCluster}" />

我想将 SelectedItem 绑定到我的模型上的一个属性.

I want to bind the SelectedItem to a property on my Model.

但这给了我错误:

'SelectedItem' 属性是只读的，不能从标记中设置.

'SelectedItem' property is read-only and cannot be set from markup.

好的，这就是我解决这个问题的方法:

Ok, this is the way that I solved this:

<TreeView
          ItemsSource="{Binding Path=Model.Clusters}" 
          ItemTemplate="{StaticResource HoofdCLusterTemplate}"
          SelectedItemChanged="TreeView_OnSelectedItemChanged" />

在我的 xaml 的代码隐藏文件中:

and in the codebehindfile of my xaml:

private void TreeView_OnSelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
{
    Model.SelectedCluster = (Cluster)e.NewValue;
}

推荐答案

我意识到这已经有一个答案被接受，但我把它放在一起来解决问题.它使用与 Delta 的解决方案类似的想法，但不需要对 TreeView 进行子类化:

I realise this has already had an answer accepted, but I put this together to solve the problem. It uses a similar idea to Delta's solution, but without the need to subclass the TreeView:

public class BindableSelectedItemBehavior : Behavior<TreeView>
{
    #region SelectedItem Property

    public object SelectedItem
    {
        get { return (object)GetValue(SelectedItemProperty); }
        set { SetValue(SelectedItemProperty, value); }
    }

    public static readonly DependencyProperty SelectedItemProperty =
        DependencyProperty.Register("SelectedItem", typeof(object), typeof(BindableSelectedItemBehavior), new UIPropertyMetadata(null, OnSelectedItemChanged));

    private static void OnSelectedItemChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        var item = e.NewValue as TreeViewItem;
        if (item != null)
        {
            item.SetValue(TreeViewItem.IsSelectedProperty, true);
        }
    }

    #endregion

    protected override void OnAttached()
    {
        base.OnAttached();

        this.AssociatedObject.SelectedItemChanged += OnTreeViewSelectedItemChanged;
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();

        if (this.AssociatedObject != null)
        {
            this.AssociatedObject.SelectedItemChanged -= OnTreeViewSelectedItemChanged;
        }
    }

    private void OnTreeViewSelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
    {
        this.SelectedItem = e.NewValue;
    }
}

然后您可以在 XAML 中使用它:

You can then use this in your XAML as:

<TreeView>
    <e:Interaction.Behaviors>
        <behaviours:BindableSelectedItemBehavior SelectedItem="{Binding SelectedItem, Mode=TwoWay}" />
    </e:Interaction.Behaviors>
</TreeView>

希望对某人有所帮助！

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